A quality choiceNASA
picks Rice's Daniel Cohan for Air Quality Applied Sciences Team

BY MIKE WILLIAMSRice News staff

Daniel Cohan, an assistant professor in civil and environmental
engineering at Rice, has been appointed by NASA to a new Air Quality Applied
Sciences Team (AQAST). The team will pursue innovative applications
of satellite and other data to inform air-quality management.

Cohan, a Fulbright scholar and recipient of a prestigious National
Science Foundation CAREER Award, is one of 19 American scientists to win
five-year NASA grants. Their research and recommendations will help the
agency best utilize the massive amount of data produced by instruments
above Earth.

DANIEL
COHAN

Team members are experts in remote sensing, modeling and air-quality
management, according to the AQAST website, and "have the resources to
carry out quick-turnaround research responding to urgent and evolving
needs."

The group will meet for the first time in Boulder, Colo., in May.

Cohan said NASA has made great strides in recent years in its ability
to see and analyze pollution from space. "NASA has spent hundreds of
millions of dollars to launch satellites that measure air pollutants,
and the purpose of the applied sciences team is to take that data and
put it to better use, to inform science and air-quality management," he
said.

"What's really exciting is that the generation of satellite devices
deployed over the past decade has enormously expanded the opportunities
for research. They have better sensors, and scientists at NASA and in
Europe have developed new technology for taking the signals they receive
from space and creatively using them to get increasingly accurate
estimates of pollution.

"For example," he said, "10 years ago the best you could get to
estimate levels of nitrogen dioxide was a resolution of about 100
kilometers. Now we're getting resolutions on the order of 10-20
kilometers."

That's important in Houston, he said, "where we're trying to resolve
emissions from the Ship Channel and an urban area. At that resolution,
you can start to make some headway in understanding what's happening on
an urban-to-regional scale."

Cohan said that until recent years, satellites gave scientists
readings of nitrogen dioxide for a particular area only once every six
days. Now there's a pass once a day, and he looks forward to a time when
geosynchronous satellites "can give around-the-clock measurements of
pollutants of interest."

The new group will be led by Cohan's undergraduate adviser, Daniel
Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and
Environmental Engineering at Harvard University, and will include his
Ph.D. adviser, Armistead Russell, the Georgia Power Distinguished
Professor of Environmental Engineering at Georgia Tech.

While the results of the group's efforts remain an open book, the
approach follows a well-established NASA model, Cohan said. "In other
areas, including space exploration, NASA has formed teams of scientists
to advise its direction, but they've never attempted to do this for air
quality," he said. "They decided this would be a great way to catalyze
research."

Data generated by NASA plays a key role in that process. "We are
using NASA satellite measurements of nitrogen dioxide to infer the rates
of emissions coming from cars and factories," he said. "It's
interesting to look bottom-up at what you think is coming out of those
sources, and top-down from space at how much of this pollution is
actually out there, to see if they're consistent. If not, that points to
gaps in our current understanding that might be interesting to
explore."

Cohan said he would bring unique experience to the team. "Unlike most
scientists, I actually worked for a state agency (as an air quality
expert for the Georgia Environmental Protection Division) before coming
to Rice, helping develop air pollution strategies for the state. I'm
sure we'll be thinking about how to take satellite and modeling results
and use them to improve the decision-making process."

He anticipates involving graduate and undergraduate students from his
research group at Rice to take part in the work.